JP6564538B1 - Endoscope light source device - Google Patents

Abstract

A light source driver (42) that applies the first and second drive currents to the B-LDs (45a, 45b) that generate laser beams of the same color, and the current values of the first and second drive currents are A control unit that controls the light source driving unit (42) so as to perform current dimming with a maximum pulse width when the speckle suppression current value is larger than the speckle suppression current value and to perform pulse width dimming when equal to the speckle suppression current value. (41) and an endoscope light source device (40).

Description

  The present invention relates to an endoscope light source device including a plurality of laser light sources that generate light of the same color.

  An endoscope light source device that generates illumination light for an endoscope has been proposed that uses a semiconductor light source.

  For example, Japanese Patent No. 6138203 discloses a technique for performing dimming control in an endoscope apparatus including a plurality of LEDs as light sources while maintaining a color balance at an optimum value. Specifically, when a PWM pulse is applied to the LED as the drive current, for example, when dimming from the maximum light amount to the minimum light amount, the current value is controlled from the maximum current value to the minimum current value with the pulse width maximized. When the current value reaches the minimum current value, the control shifts to PWM dimming, and the pulse width is sequentially reduced.

  By the way, when using a laser light source as a semiconductor light source of an endoscope light source device, it is known that speckles in which a speckled pattern is formed may occur due to random interference. This speckle is suppressed to a low level in a region where the current value of the drive current applied to the laser light source is high, but is likely to occur at a high level in a region where the current value of the drive current is low.

  Therefore, even if it is within the range of the rated current value of the laser light source, an operation for suppressing speckles can be considered by avoiding the use of a low current value region where speckles are likely to occur. However, in this case, the dimming characteristics are deteriorated, for example, the dimming dynamic range becomes narrow and the gradation reproducibility also decreases.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an endoscope light source device that can suppress speckle of a laser light source and realize good dimming characteristics. .

In the endoscope light source device according to one aspect of the present invention, the first drive current is applied, and the current value of the first drive current is used as part of the illumination light from the endoscope inserted into the subject. A first laser light source that generates a first laser light having an intensity corresponding to the first laser light source, and a first pulse value having a first current value that is equal to or less than a maximum rated current value of the first laser light source. A first application unit that applies a drive current to the first laser light source; and a second drive current that is applied, and has an intensity corresponding to a current value of the second drive current. A second laser light source that generates a second laser light of the same first color as the color as part of the illumination light from the endoscope, and a second pulse width of the second laser light source a second application unit for applying the second driving current of maximum rated current value or less of the second current value to the second laser light source, A part of the illumination light from the endoscope is applied with a light having a second color different from the first color and having an intensity corresponding to the current value of the third drive current. A light source generated as follows: a third application unit that applies a third drive current having a third pulse width that is equal to or less than a maximum rated current value of the light source to the light source; The first threshold value, which is set to suppress the speckle of the laser beam of the first laser light source, which is larger than the minimum rated current value of the first laser light source, and the speckle of the second laser beam are suppressed. And the second threshold value set to be a second threshold value that is a current value larger than the minimum rated current value of the second laser light source, the first current value is greater than the first threshold value. If it is larger, the first pulse width is set to the maximum pulse width so that the current dimming is performed. The application unit is controlled, and when the second current value is larger than the second threshold, the second application unit is configured to perform current dimming by setting the second pulse width to the maximum pulse width. Controlling and performing the first control for causing the first application unit and the second application unit to perform current dimming, the first current value becomes equal to the first threshold value, In addition, when the second current value becomes equal to the second threshold value and the control for further reducing the light amount is required, the second current value is supplied to the second application unit. While maintaining the state in which the second pulse width is equal to the second threshold and the maximum pulse width being maintained, the first application unit has a state in which the first current value is equal to the first threshold. A light source control unit that shifts to a second control for controlling to perform pulse width dimming while maintaining; Have a, the light source control unit, said third current value is greater than the minimum rated current value of the light source performs a current dimming, the minimum rated current value pulse width adjustment is equal to the light source The third application unit is controlled to perform light, and the light source control unit is based on a first intensity of the first color light and a second intensity of the second color light. The first application unit, the second application unit, and the third application unit so that the first color light and the second color light are maintained in a predetermined color balance. And the light source controls the first current value when the light source controller performs control to reduce the light amount while maintaining the predetermined color balance. In the frame after the frame in which the first threshold value is reached, the third current value is the highest. The minimum rated current value is set so as to reach the rated current value, and the light source control unit performs control to reduce the light amount while maintaining the predetermined color balance. Controls to set the first pulse width in the current frame based on the intensity ratio when performing the current dimming on the frame, where the intensity ratio is the first pulse A target in the current frame for the second intensity in a frame where the width reaches the first threshold at the maximum pulse width and the second pulse width reaches the second threshold at the maximum pulse width; The ratio of the second intensity.
In the endoscope light source device according to another aspect of the present invention, the first driving current is applied, and the current of the first driving current is used as a part of the illumination light from the endoscope inserted into the subject. A first laser light source that generates a first laser beam having an intensity corresponding to the value; and a first pulse current having a first current value equal to or less than a maximum rated current value of the first laser light source with a first pulse width. A first application unit that applies a first drive current to the first laser light source, and a second drive current applied to the first laser light having an intensity corresponding to a current value of the second drive current. A second laser light source that generates a second laser light of the same first color as the color of the second laser light source as a part of the illumination light from the endoscope, and the second laser light source with a second pulse width A second application unit for applying the second drive current having a second current value equal to or less than a maximum rated current value to the second laser light source; A third driving current is applied, and light of a second color different from the first color having an intensity corresponding to the current value of the third driving current is used as one of the illumination lights from the endoscope. A light source generated as a unit, a third application unit configured to apply a third drive current having a third current value equal to or less than a maximum rated current value of the light source to the light source with a third pulse width; A first threshold value which is set to suppress speckle of one laser beam and is larger than a minimum rated current value of the first laser light source, and speckle of the second laser beam. Based on the second threshold value that is set to suppress and is a current value that is larger than the minimum rated current value of the second laser light source, the first current value is greater than the first threshold value. Is larger, the first pulse width is set to the maximum pulse width, current dimming is performed, and the first pulse width is If the second current value is larger than the second threshold value, the second pulse width is set to the maximum pulse. When the current dimming is performed in a width and the second application unit is controlled to perform pulse width dimming when the current dimming is equal to the second threshold value, the third current value is the minimum rated current of the light source. A light source control unit that controls the third application unit to perform current dimming when greater than the value, and to perform pulse width dimming when equal to the minimum rated current value of the light source, and The light source control unit is configured to control the first color light and the second color light based on a first intensity of the first color light and a second intensity of the second color light. Are maintained at a predetermined color balance, the first application unit, the second application unit, and the third application unit. Control to perform light amount control in frame units, and whether to perform current dimming or pulse width dimming is the same for the first application unit and the second application unit. The light source is controlled such that the first current value is the first threshold value when the light source controller performs control to reduce the light amount while maintaining the predetermined color balance. The minimum rated current value is set so that the third current value reaches the minimum rated current value in a frame after the frame that has reached A, and further, the light source controller When the third application unit performs control for reducing the light amount while maintaining a predetermined color balance, the intensity ratio is multiplied by the maximum pulse width of the first pulse width. Value in the current frame The first pulse width and the second pulse width are controlled to be set, wherein the intensity ratio is such that the first pulse width reaches the first threshold value with a maximum pulse width, and The ratio of the second intensity as a target in the current frame to the second intensity in the frame in which the second pulse width reaches the second threshold with the maximum pulse width.

The figure which shows the structure of the endoscope system in Embodiment 1 of this invention. In the said Embodiment 1, the diagram which shows an example of the relationship between the speckle which generate | occur | produces in a laser light source, and an electric current value. In the said Embodiment 1, the timing chart which shows the mode of the drive of each light emitting element at the time of light control from the maximum light quantity to the minimum light quantity. In the said Embodiment 1, the figure which shows the example of the current light control with respect to a laser light source, and pulse width light control. In the said Embodiment 1, the diagram which shows a mode that the color balance of each color light is maintained even if it changes a light quantity. 7 is a flowchart showing a flow of light amount control in the endoscope light source device of the first embodiment. 7 is a flowchart showing details of a G light amount reduction process in FIG. 6 of the first embodiment. The flowchart which shows the detail of the process of B light quantity reduction | decrease in FIG. 6 of the said Embodiment 1. FIG. In Embodiment 2 of this invention, the timing chart which shows the mode of the drive of each light emitting element concerning B color light and G color light at the time of light control from the maximum light quantity to the minimum light quantity. 9 is a flowchart showing processing for reducing the amount of B light in the endoscope light source device according to the second embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1]
1 to 8 show a first embodiment of the present invention, and FIG. 1 is a diagram showing a configuration of an endoscope system 1.

  The endoscope system 1 includes an endoscope 10, a video processor 20, a monitor 30, and an endoscope light source device 40 (hereinafter abbreviated as a light source device 40).

  The endoscope 10 has an elongated insertion portion 11 that can be inserted into a subject on the distal end side. Here, the subject is an object to be examined, for example, inside a body cavity of a human body, a living body other than a human body, or an object other than a living body such as an engine plant.

  An imaging unit 13 including an objective optical system that forms an optical image of the subject and an imaging element that captures the optical image formed by the objective optical system and outputs an imaging signal is provided at the distal end of the insertion unit 11. It has been. Here, the objective optical system has, for example, one or more optical lenses and an optical diaphragm. Further, the imaging element is configured to include a sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). Thus, although the endoscope 10 of the present embodiment is configured as an imaging apparatus having an imaging function, the present invention is not limited to this, and an optical endoscope that performs optical observation may be used.

  Furthermore, an illumination lens 14 for irradiating the subject with illumination light transmitted from the light source device 40 via the light guide 15 is disposed at the distal end portion of the insertion portion 11.

  In other words, the exit end surface, which is the front end surface of the light guide 15, is arranged at a position where the illumination lens 14 is irradiated with illumination light. The light guide 15 is disposed in the insertion portion 11 along the longitudinal direction of the insertion portion 11, and further extends into the connector 12 provided on the proximal end side of the endoscope 10.

  The connector 12 is a connection part that detachably connects the endoscope 10 to the light source device 40. When the connector 12 is connected to the connector receiver of the light source device 40, the incident end surface, which is the base end surface of the light guide 15, is arranged at the illumination light receiving position in the light source device 40.

  A signal line 16 is connected to the imaging unit 13 described above. The signal line 16 is disposed in the insertion portion 11 along the longitudinal direction of the insertion portion 11. A cable 17 extends from the endoscope 10 and is detachably connected to the video processor 20 by a connector 18 provided at a distal end portion of the cable 17. The signal line 16 extends in the cable 17 and is connected to the connector 18.

  With such a configuration, the imaging unit 13 is electrically connected to the video processor 20 via the signal line 16 and the connector 18.

  The video processor 20 is an image processing device that drives the imaging unit 13 and processes an imaging signal obtained from the imaging unit 13.

  That is, the video processor 20 generates a drive signal including a synchronization signal, supplies the drive signal to the imaging unit 13, and drives the imaging unit 13 while controlling the operation. Thereby, the imaging unit 13 performs imaging, for example, in units of frames, generates a moving image, and outputs it as an imaging signal. The imaging signal output from the imaging unit 13 in this way is transmitted to the video processor 20.

  The video processor 20 performs signal processing on the imaging signal to generate an image signal that can be displayed on the monitor 30. The video processor 20 outputs the generated image signal to the monitor 30 via the cable 21 that connects the video processor 20 and the monitor 30. Thereby, an endoscopic image is displayed on the display screen of the monitor 30.

  Further, the video processor 20 detects the brightness of the image based on the imaging signal obtained from the imaging unit 13. Then, the video processor 20 generates a light source control signal for controlling the light source device 40 so that the brightness of the detected image becomes the brightness of the target image. Here, an example of the light source control signal is information on the ratio of the target brightness of the current frame image to be acquired next to the brightness of the acquired image of the latest frame (however, the present invention is not limited to this). Absent). The light source control signal is output from the video processor 20 and transmitted to the light source device 40 via the communication cable 22 that connects the video processor 20 and the light source device 40.

  The light source device 40 includes a control unit 41, a light source driving unit 42, an R-LED 43 (R: red, LED: Light Emitting Diode), a lens 43l, an R light sensor 43s, and a G-LED 44 (G: green). A lens 44l, a G light sensor 44s, a first B-LD 45a (B: blue, LD: Laser Diode), a second B-LD 45b, a multiplexing unit 45c, a lens 45l, a B light sensor 45s, A dichroic filter 46, a dichroic filter 47, a lens 48, and an operation panel 49 are provided.

  The control unit 41 is connected to the light source driving unit 42, the R light sensor 43 s, the G light sensor 44 s, the B light sensor 45 s, and the operation panel 49. Based on the operation input from the operation panel 49, the sensor outputs of the R light sensor 43s, the G light sensor 44s, and the B light sensor 45s, and the light source control signal from the video processor 20, the control unit 41 It is a light source control unit that outputs dimming information to the drive unit 42 and controls the inside of the light source device 40.

  The control unit 41 includes a nonvolatile storage unit inside. In this storage unit, a light quantity ratio of R light, G light, and B light for constituting white light (for example, a light quantity ratio Crg of R light to G light when G light is used as a reference, and B light to G light) The light quantity ratio Cbg) is stored. Further, the storage unit of the control unit 41 has a table showing the relationship between the current value of the drive current and the light emission intensity for each of the R-LED 43, the G-LED 44, the first B-LD 45a, and the second B-LD 45b. It is remembered.

  And the control part 41 of the drive current applied as a pulse with respect to R-LED43, G-LED44, 1B-LD45a, and 2nd B-LD45b which are light emitting elements (more specifically, semiconductor light-emitting device). The current value and the pulse width are output as dimming information to the light source driving unit 42. The dimming information is such that the brightness of the target image indicated by the light source control signal from the video processor 20 is achieved, and the light quantity ratio of the R light, G light, and B light constituting the white light is maintained. Current value and pulse width.

  In this way, the light emission amount control (dimming) of each light-emitting element by the light source driving unit 42 is performed by applying current dimming by controlling the current value of the driving current and applying a pulsed current within one frame. And pulse width dimming (by so-called PWM (Pulse Width Modulation)). As a unit representing the pulse width, for example, a duty ratio is used.

  The light source drive unit 42 applies a pulsed drive current to the R-LED 43, G-LED 44, the first B-LD 45a, and the second B-LD 45b, which are light emitting elements, based on the dimming information of the control unit 41 to emit light. To do.

  The light source drive unit 42 has a first pulse width PWb1, a first application unit that generates a first drive current having a first current value Ib1 that is equal to or less than the maximum rated current value Imax (B1), and a second pulse width. The maximum rated current at the second application unit that generates the second drive current of the second current value Ib2 equal to or less than the maximum rated current value Imax (B2) at the PWb2 and the third pulse width PWg (or PWr) This also serves as a third application unit that generates a third drive current having a third current value Ig (or Ir) equal to or less than the value Imax (G) (or Imax (R)).

  In other words, the first application unit is a functional unit of the light source driving unit 42 that applies the first driving current to the first B-LD 45a. The second application unit is a functional unit of the light source drive unit 42 that applies the second drive current to the second B-LD 45b. Furthermore, the third application unit is a functional unit of the light source drive unit 42 that applies a third drive current to the R-LED 43 and the G-LED 44, respectively.

  Thus, each light emitting element emits light for the light emission period corresponding to the duty ratio of the PWM pulse at the light emission intensity corresponding to the current value of the drive current applied from the light source driving unit 42 in the imaging period of one frame. ing.

  The R-LED 43 receives the driving current from the light source driving unit 42 and emits red light (R light) with a light emission intensity corresponding to the third current value Ir in a light emission period of the third pulse width PWr. .

  The lens 43l is disposed on the optical path of the emitted light from the R-LED 43, converts the light emitted from the R-LED 43 into substantially parallel light, and emits it.

  The R light sensor 43 s detects the intensity of the R light emitted from the R-LED 43.

  The G-LED 44 receives the driving current from the light source driving unit 42 and emits green light (G light) in the light emission period of the third pulse width PWg with the light emission intensity corresponding to the third current value Ig. . Therefore, the third pulse width PWg is the pulse width of the third drive current of the G-LED 44.

  That is, the R-LED 43 and the G-LED 44 are applied with the third drive current from the light source drive unit 42, and are different in intensity from the first color (blue) according to the third current values Ir and Ig. It is a light source that generates light of two colors (red or green) as part of illumination light from the endoscope 10.

  The lens 44l is disposed on the optical path of the emitted light from the G-LED 44, converts the light emitted from the G-LED 44 into substantially parallel light, and emits it.

  The G light sensor 44 s detects the intensity of the G light emitted from the G-LED 44.

  The R light sensor 43 s and the G light sensor 44 s described above are second light detection units that receive light generated by the light sources (R-LED 43 and G-LED 44) and detect the second intensity of the incident light. is there.

  The first B-LD 45a is applied with the first drive current from the light source drive unit 42 which is the first application unit, and the first laser light (blue light: B light) having an intensity corresponding to the first current value Ib1. Is a first laser light source that is generated as part of the illumination light from the endoscope 10 during the light emission period of the first pulse width PWb1. Therefore, the first pulse width PWb1 is the pulse width of the first drive current of the first B-LD 45a.

  The second B-LD 45b is applied with the second drive current from the light source drive unit 42, which is the second application unit, and has the same intensity as the first laser light having the intensity corresponding to the second current value Ib2. Is a second laser light source that is generated as a part of illumination light from the endoscope 10 during the light emission period of the second pulse width PWb2. Therefore, the second pulse width PWb2 is the pulse width of the second drive current of the second B-LD 45b.

  Although two LDs that emit blue light are provided here, three or more LDs may be provided. Here, R and G are LEDs and B is LD. However, the present invention is not limited to this combination, and one or more arbitrary colors may be LD and the other colors may be LEDs.

  The multiplexing unit 45c combines and emits the light emitted from the first B-LD 45a and the light emitted from the second B-LD 45b. Since the laser light source has a small light emission area, for example, by using an optical fiber or the like as the multiplexing unit 45c, multiplexing can be performed relatively easily.

  The lens 45l is disposed on the optical path of the emitted light from the multiplexing unit 45c, converts the light emitted from the multiplexing unit 45c into substantially parallel light, and emits it.

  The B light sensor 45s is a first light detection unit that receives the first laser light and the second laser light and detects the first intensity of the incident light. That is, the B light sensor 45s is a laser light detector that detects the intensity of the B light combined by the combining unit 45c.

  The R light sensor 43s, the G light sensor 44s, and the B light sensor 45s in this embodiment are non-integrating types that convert received light into electrical signals in real time (that is, time-integrates the emission intensity within one frame). This is assumed to be a type different from the integral type that detects the light emission amount of one frame).

  Here, the first light detection unit is configured as a laser light detector that receives the combined light obtained by adding the first laser light and the second laser light and detects the intensity of the incident combined light. However, it is not limited to this.

  For example, the first light detection unit receives the first laser light, the first laser light detector that detects the intensity of the incident first laser light, and the second laser light is incident. And a second laser beam detector that detects the intensity of the incident second laser beam (that is, a first B photosensor that detects B light emitted from the first B-LD 45a) And a second B light sensor that detects the B light emitted from the second B-LD 45b.

  The dichroic filter 46 is disposed at a position where the optical axis of the lens 43l and the optical axis of the lens 44l intersect. The dichroic filter 46 transmits the R light from the R-LED 43 and reflects the G light from the G-LED 44. Thus, the R light and the G light are combined by the dichroic filter 46.

  The dichroic filter 47 is disposed at a position where the optical axis of the lens 43l and the optical axis of the lens 45l intersect. The dichroic filter 46 transmits the R light from the R-LED 43 and the G light from the G-LED 44, and reflects the B light from the multiplexing unit 45c. In this way, the dichroic filter 47 combines the R light, the G light, and the B light into white light.

  Although the present embodiment will be described assuming that white light illumination is performed simultaneously, the dimming control described below is similarly applied even when white light illumination is performed in a surface sequential manner. can do.

  The lens 48 irradiates white light from the dichroic filter 47 to the incident end face of the light guide 15 as parallel light.

  The operation panel 49 includes, for example, a touch panel and operation switches, and is an operation unit that performs settings for the light source device 40 when operated by a user. A signal generated by operating the operation panel 49 is input to the control unit 41. The operation panel 49 can display the current setting value of the light source device 40 and the like.

  FIG. 2 is a diagram showing an example of the relationship between speckles generated in the laser light source and current values.

  As shown in the figure, when the current value of the drive current applied to the laser light source is less than a certain current value, the coherence of the laser beam is higher than in the case where the current value is more than a certain current value. The contrast is high. Here, the speckle contrast is an index generally used as an evaluation index for speckle, and is defined by a ratio of a standard deviation to an average value of luminance. Therefore, a threshold current value (coherence threshold current value) that is a large or small division of the speckle contrast value is set as the speckle suppression current value Isp-th. As will be described later, the speckle suppression current value Isp-th is a value that falls within the range of the rated current value of the laser light source (the range between the minimum rated current value Ith and the maximum rated current value Imax). Specifically, the speckle suppression current value Isp-th is a value satisfying Ith <Isp-th <Imax. The minimum rated current value Ith is assumed to be the minimum current value at which the laser is oscillated from the laser light source, that is, the laser oscillation threshold, but is not limited to this.

  The speckle suppression current value Isp-th related to the first B-LD 45a is larger than the minimum rated current value Ith of the first B-LD 45a set to suppress speckle of the first laser beam. Is the first threshold value.

  The speckle suppression current value Isp-th related to the second B-LD 45b is larger than the minimum rated current value Ith of the second B-LD 45b, which is set to suppress the speckle of the second laser beam. Is the second threshold value.

  3 is a timing chart showing how each light emitting element is driven when dimming from the maximum light amount to the minimum light amount, FIG. 4 is a diagram showing an example of current dimming and pulse width dimming for the laser light source, and FIG. It is a diagram which shows a mode that the color balance of each color light is maintained even if it changes.

  First, as shown in FIG. 5, the G light with any light amount from when the white light combined by the dichroic filter 47 is the maximum light amount Lmax (R + G + B) to when it is the minimum light amount Lmin (R + G + B). The dimming is performed so that the ratio of the light quantity L (G), the light quantity L (R) of the R light, and the light quantity L (B) of the B light is kept constant.

  As described above, the dimming is performed by the ratio Crg of the R light amount L (R) to the G light amount L (G) and the ratio of the B light amount L (B) to the G light amount L (G). The control unit 41 generates the dimming information so that Cbg is always kept constant.

  Further, as described above, dimming of each light emitting element is performed by current dimming and pulse width dimming, and specifically, as shown in FIG.

  That is, the first B-LD 45a and the second B-LD 45b which are laser light sources have the maximum light amount Lmax when the maximum rated current value Imax is applied with the pulse width as the maximum pulse width (duty ratio 100%). In addition, although 100% was mentioned here as an example of the duty ratio corresponding to the maximum pulse width, it is not limited to this. For example, when the exposure possible period is shorter than the frame period, the pulse width when light is emitted over the entire exposure possible period is the maximum pulse width. As a specific example in which the exposure possible period of all lines is shorter than the frame period, in the rolling shutter type exposure in which the exposure start timing and the exposure end timing are shifted for each line, the exposure is started from the timing when the last line starts exposure. The entire line exposure period is until the end of exposure of the first line.

  When dimming to reduce the light amount from the maximum light amount Lmax, first, current dimming to reduce the current value is performed while maintaining the maximum pulse width (duty ratio 100%). This current dimming is performed until the current value reaches the speckle suppression current value Isp-th. In FIG. 4, the light quantity at this time is described as L (Isp-th).

  When the current value reaches the speckle suppression current value Isp-th, the process proceeds to pulse width dimming. That is, pulse width dimming is performed by reducing the pulse width (that is, reducing the duty ratio) while maintaining the current value at the speckle suppression current value Isp-th. This pulse width dimming is performed until the pulse width reaches the minimum pulse width PWmin.

  Thus, when the current value is the speckle suppression current value Isp-th and the pulse width is the minimum pulse width PWmin, the minimum light amount Lmin is obtained. Therefore, a current value range that is greater than or equal to the minimum rated current value Ith and less than the speckle suppression current value Isp-th is not used for causing the laser light source to emit light. Thereby, the speckle of a laser beam can be suppressed.

  Further, the laser light source (the first B-LD 45a and the second B-LD 45b) is set to non-emission (even if the generation of light does not become completely zero, it may be in a state where the amount of light can be regarded as substantially zero). In this case, as shown in FIG. 4, the pulse width is set to the minimum pulse width PWmin, and the current value is set to the standby current value Istby that is greater than 0 and less than the minimum rated current value Ith. This is because, if the current value is set to 0, overshoot or the like occurs when a current is applied to emit light again, and it may take time for the light intensity to stabilize.

  Although FIG. 4 shows an example of a laser light source, the speckle suppression current value Isp-th can be replaced with the minimum rated current value Imin for dimming of the LEDs (R-LED 43, G-LED 44). Almost similar graphs can be applied.

  That is, dimming that reduces the light amount from the maximum light amount Lmax is also performed on the LEDs by current dimming. This current dimming is performed until the current value reaches the minimum rated current value Imin. Then, the process shifts to pulse width dimming. For the LED, when the light is not emitted, the current value is set to 0, for example (however, when the intensity of light when shifting from the non-light emission to the light emission becomes unstable as in the case of the LD, The standby current value Istby may be larger than 0 and less than the minimum rated current value Imin).

  Thus, the control unit 41 sets the first pulse width PWb1 to the maximum pulse width when the first current value Ib1 is larger than the first threshold value (speckle suppression current value Isp-th according to the first B-LD 45a). Current dimming is performed at 100%, and if it is equal to the first threshold, the light source driving unit 42 is controlled to perform pulse width dimming.

  Further, when the second current value Ib2 is larger than the second threshold value (speckle suppression current value Isp-th related to the second B-LD 45b), the control unit 41 sets the second pulse width PWb2 to the maximum pulse width. Current dimming is performed at 100%, and if it is equal to the second threshold value, the light source drive unit 42 is controlled to perform pulse width dimming.

  Further, the control unit 41 performs current dimming when the third current values Ir and Ig are larger than the minimum rated current value Imin of the light source (R-LED 43, G-LED 44), and the minimum rated current value of the light source. When equal to Imin, the light source driving unit 42 is controlled to perform pulse width dimming.

  In the case of dimming from the maximum light amount to the minimum light amount, each light emitting element is driven as shown in FIG. 3, for example. Here, the control unit 41 performs light amount control in units of frames.

  In the frame F1, each light emitting element (R-LED 43, G-LED 44, first B-LD 45a, second B-LD 45b) receives a driving current having a maximum pulse width of 100% and a maximum rated current value Imax within one frame period FP. Apply and emit at maximum light intensity.

  Note that the maximum rated current value Imax and the minimum rated current values Ith and Imin may be different values for each light emitting element, and the speckle suppression current value Isp-th may be different values for each laser light source. Absent. Therefore, as an example in FIG. 3, the maximum rated current value of the R-LED 43 is Imax (R), the maximum rated current value of the G-LED 44 is Imax (G), and the maximum rated current value of the first B-LD 45a is Imax (B1). ), The maximum rated current value of the second B-LD 45b is described as Imax (B2).

  Further, the maximum rated current values Imax (R), Imax (G), Imax (B1), and Imax (B2) are determined by the light emitting elements (R-LED43, G-LED44, 1B-LD45a, 2B-LD45b). In the frame F1 that emits light with the maximum light amount, the white balance is set.

That is, the maximum light amount obtained when each light emitting element emits light with the maximum pulse width of 100% and the maximum rated current values Imax (R), Imax (G), Imax (B1), and Imax (B2) is expressed as Lmax (R). , Lmax (G), Lmax (B) (where Lmax (B) = Lmax (B1) + Lmax (B2)),
Crg = {Lmax (R) / Lmax (G)}
Cbg = {Lmax (B) / Lmax (G)}
The maximum rated current values Imax (R), Imax (G), Imax (B1), and Imax (B2) are set so that

  And in the period of the frames F1-F3 shown in FIG. 3, all the light emitting elements are controlled by current dimming.

  The control unit 41 applies the first B-LD 45a to the first B-LD 45a when performing the first control for causing the light source driving unit 42 to perform the current dimming of the first B-LD 45a and the second B-LD 45b (frames F1 to F3). The first current value Ib1 is equal to the speckle suppression current value Isp-th, and the second current value Ib2 applied to the second B-LD 45b is equal to the speckle suppression current value Isp-th. When the control for further reducing the light amount is necessary, the process proceeds to the second control.

  Then, in the second control, the control unit 41 causes the light source drive unit 42 to make the second current value Ib2 equal to the speckle suppression current value Isp-th and the second pulse width PWb2 to be the maximum pulse width 100%. While maintaining the state, control is performed so that pulse width dimming is performed while maintaining the state where the first current value Ib1 is equal to the speckle suppression current value Isp-th (frames F4 to F7).

  That is, the control unit 41 performs control so that current dimming or pulse width dimming is set individually for the first application unit and the second application unit.

  Here, in the frames F4 and F5, only the first B-LD 45a has pulse width dimming, but in the frames F6 and F7, the R-LED 43 and G-LED 44 also have pulse width dimming.

  When the control unit 41 is performing the second control and the first pulse width PWb1 becomes the minimum pulse width PWmin (frame F7), the control for further reducing the light amount is necessary. Then, the process proceeds to the third control.

  Then, in the third control, the control unit 41 causes the light source driving unit 42 to maintain the state in which the first pulse width PWb1 is the minimum pulse width PWmin, while the second current value Ib2 is the speckle suppression current. Control is performed to perform pulse width dimming while maintaining a state equal to the value Isp-th (frames F8 to F10).

  When shifting to the third control, the control unit 41 first causes the light source driving unit 42 to set the first current value Ib1 to the standby current value Istby (frame F8), and then the second B-LD 45b. Control is performed to perform pulse width dimming (frames F9 to F10).

  Next, dimming with white balance maintained in the control example shown in FIG. 3 will be described using the G-LED 44, the first B-LD 45a, and the second B-LD 45b as examples.

  First, the control unit 41 sets the light amount of light of another color with reference to the light amount of light of one color. In the present embodiment, as described above, an example in which the control unit 41 stores the light amount ratios Crg and Cbg and sets the light amounts of the R light and the B light on the basis of the G light will be described. However, light of another color may be used as a reference, and the light is not limited to light of one color.

  The amount of emitted light can be obtained by time-integrating the intensity of the emitted light. At this time, if light is emitted with a rectangular light intensity using a rectangular PWM pulse, the light quantity is proportional to a value obtained by multiplying the light intensity and the pulse width. Among these, the pulse width is obtained from the light source driving unit 42. On the other hand, the light intensity is obtained as a detection result of the R light sensor 43s, the G light sensor 44s, and the B light sensor 45s in the present embodiment.

  As described above, in the present embodiment, it is assumed that the R light sensor 43 s, the G light sensor 44 s, and the B light sensor 45 s are non-integrating types. A sensor value other than zero is output, but the sensor value becomes zero when no light is emitted. Accordingly, the intensity Sg of G light obtained by the G light sensor 44s, the intensity Sb of B light obtained by the B light sensor 45s, and the intensity Sr of R light obtained by the R light sensor 43s as described below are as follows. It is assumed that the sensor value is In particular, the intensity Sb of B light is a sensor value detected during the W light emission period when there is a W light emission period during which the first B-LD 45a and the second B-LD 45b emit light within one frame. And

  However, the R light sensor 43 s, the G light sensor 44 s, and the B light sensor 45 s are omitted, and the table stored in the control unit 41 as described above based on the current value of the drive current applied to each light emitting element. The light emission intensity may be obtained by referring to (a table showing the relationship between the current value of the drive current and the light emission intensity). Alternatively, the light emission intensity may be calculated based on the current value using a mathematical formula or the like instead of the table. For example, when α and β are constants, a linear relationship S = (α × I + β) is approximately established between the current value I of the drive current and the light emission intensity S, and therefore, calculation is performed using this linear format. Alternatively, it may be calculated using a more complicated nonlinear function or the like.

  Thus, the control unit 41 has a first intensity of the first color (blue) light (in this embodiment, the first intensity Sb detected by the first light detection unit (B light sensor 45s)), and Second intensity of the second color (red or green) light (in this embodiment, second intensities Sr, Sg detected by the second light detection unit (R light sensor 43s, G light sensor 44s)) ) So that the light of the first color (blue) and the light of the second color (red or green) are maintained in a predetermined color balance (color balance represented by the light amount ratios Crg and Cbg). In addition, the light source driving unit 42 is controlled.

  First, regarding the G light, the control unit 41 sets the amount of G light to be emitted in the next frame, based on the image brightness target value included in the light source control signal from the video processor 20. When the set amount of G light is larger than the pulse width 100% × (intensity of light emitted from the G-LED 44 at the minimum rated current value Imin), current control is performed, and when the light amount is less than the pulse width, The third pulse width PWg and the third current value Ig of the third drive current applied to the G-LED 44 are determined so as to perform control. Accordingly, the third pulse width PWg and the third current value Ig relating to the G light are determined based on the light source control signal from the video processor 20.

  On the other hand, for light of a color other than the G light (here, the B light will be described), in the example shown in FIG. 3, the following is based on the third pulse width PWg and the third current value Ig relating to the G light: To be determined.

  First, in the frames F1 to F3, as described above, current dimming is performed for all of the G-LED 44, the first B-LD 45a, and the second B-LD 45b. Then, after setting PWb1 = 100% and PWb2 = 100%, the first current value Ib1 of the first drive current of the first B-LD 45a so that the intensity of the B light becomes Sb = Cbg × Sg, The second current value Ib2 of the second drive current of the second B-LD 45b is determined. Here, the first current value Ib1 and the second current value Ib2 may be different values or the same value, but the first B-LD 45a and the second B-LD 45b are configured by the same product. Thus, if the control is performed so that the same current value is used during the current dimming period, the control may be simplified.

  In the frame F3, the first pulse width PWb1 reaches the maximum pulse width of 100% and the first current value Ib1 reaches the first threshold value (speckle suppression current value Isp-th related to the first B-LD 45a). In addition, the second pulse width PWb2 is the maximum pulse width 100%, and the second current value Ib2 reaches the second threshold value (speckle suppression current value Isp-th according to the second B-LD 45b).

  Therefore, in the subsequent frames F4 to F5, the pulse width dimming of the first B-LD 45a is performed while the drive control of the second B-LD 45b is maintained the same as that in the frame F3. At this time, the current dimming is continuously performed on the G-LED 44 (and the R-LED 43). That is, the frames F4 to F5 are frames in which the light source driving unit 42 functioning as the third application unit performs current dimming on the G-LED 44 and the R-LED 43.

  Here, the G-LED 44 (and the R-LED 43), which is a light source, performs control to reduce the amount of light while the control unit 41 maintains a predetermined color balance (Crg, Cbg), after the frame F3. In the frame (frame F5 in the example of FIG. 3), the third current value (current value Ir of the drive current of R-LED 43, current value Ig of the drive current of G-LED 44) reaches the minimum rated current value Imin. In addition, a minimum rated current value Imin is set.

  In the frames F4 to F5, the first current value Ib1 of the first drive current of the first B-LD 45a is the speckle suppression current value Isp-th and the second current value of the second drive current of the second B-LD 45b. Since Ib2 is also set to the speckle suppression current value Isp-th, the intensity of the B light (the intensity detected during the W light emission period described above by the non-integrating type B light sensor 45s) is the intensity at the time of the frame F3. Same as Sb (F3), and Sb = Sb (F3) = Cbg × Sg (F3). Here, Sg (F3) is the second intensity Sg in the frame F3. Hereinafter, similarly, the intensity of the light of the frame Fx is represented as S (Fx) or the like.

  The second pulse width PWb2 of the second drive current of the second B-LD 45b is set to PWb2 = 100%. The first pulse width PWb1 of the first drive current of the first B-LD 45a is set to PWb1 = [{Sg / Sg (F3)} × 200-100]. Here, Sg is a target second intensity in the current frame.

  That is, the control unit 41 maintains the second pulse width PWb2 at the maximum pulse width of 100%, and maintains the intensity ratio {Sg / Sg (F3)} to 2 of the maximum pulse width 100% of the first pulse width PWb1. A value obtained by subtracting 100% of the maximum pulse width of the first pulse width PWb1 from {{Sg / Sg (F3)} × 200] multiplied by 200% times [{Sg / Sg (F3)} × 200− 100] is set to the first pulse width PWb1 in the current frame.

  Thus, the control unit 41 performs the control for reducing the light amount while maintaining the predetermined color balance (Crg, Cbg), based on the intensity ratio {Sg / Sg (F3)} when performing the control for the frames F4 to F5. Thus, control is performed so as to set the first pulse width PWb1 in the current frame.

  In the frame F5, the third current values Ig and Ir reach the minimum rated current value Imin. Therefore, the frame F5 is a frame in which the third current value Ig reaches the minimum rated current value Imin of the light source while maintaining the second pulse width PWb2 at the maximum pulse width of 100%.

  Therefore, in the frames F6 to F7, the pulse width dimming of the first B-LD 45a is continuously performed while the drive control of the second B-LD 45b is maintained the same as that in the frame F3, and the G-LED 44 and the R-LED 43 are pulsed. Shift to width dimming. That is, the frames F <b> 6 to F <b> 7 are frames in which the light source driving unit 42 that functions as the third application unit performs pulse width dimming of the G-LED 44 and the R-LED 43.

  At this time, the control unit 41 controls the pulse width ratio {PWg / PWg (F5)} and the first pulse width PWb1 in the frame F5 as control for reducing the light amount while maintaining a predetermined color balance (Crg, Cbg). Based on (F5), control is performed to set the first pulse width PWb1 in the current frame to PWb1 = [{PWg / PWg (F5)} × {PWb1 (F5) +100} -100].

  Here, the pulse width ratio {PWg / PWg (F5)} is equal to the target third pulse width PWg in the current frame with respect to the maximum pulse width {PWg (F5) = 100%} of the third pulse width PWg. It is a ratio.

  Thus, the control unit 41 adds the pulse width to the value {PWb1 (F5) +100} obtained by adding the first pulse width PWb1 (F5) in the frame F5 and the maximum pulse width 100% of the first pulse width PWb1. The maximum pulse width 100% of the first pulse width PWb1 is subtracted from the value ([{PWg / PWg (F5)} × {PWb1 (F5) +100}]) multiplied by the ratio {PWg / PWg (F5)}. The value ([{PWg / PWg (F5)} × {PWb1 (F5) +100}] − 100) is controlled to be set to the first pulse width PWb1 in the current frame.

  In the frame F7, the first pulse width PWb1 of the first drive current applied to the first B-LD 45a reaches the minimum pulse width PWmin.

  Here, when control for further reducing the amount of light is necessary, the control unit 41 sets the first current value Ib1 to the standby current value Istby as shown in a frame F8.

  As a result, the first B-LD 45a substantially does not emit light, so the first intensity Sb detected by the B light sensor 45s is half of the first intensity Sb (F3) in the frame F3.

  Thereafter, the control unit 41 performs control so as to perform pulse width dimming with the second pulse width PWb2.

  That is, the control unit 41 multiplies the ratio {PWg / PWg (F8)} by the maximum pulse width 100% of the second pulse width PWb2 {100 × PWg / PWg (F8)} in the current frame. Control is performed so as to set the second pulse width PWb2, that is, PWb2 = {100 × PWg / PWg (F8)}.

  Here, the ratio {PWg / PWg (F8)} is a ratio of the target third pulse width PWg in the current frame to the third pulse width {PWg (F8)} in the frame F8.

  Thereafter, in the frame F10, the second pulse width PWb2 reaches the minimum pulse width PWmin (in the example of FIG. 3, in the frame F10, the third pulse widths PWg and PWr both reach the minimum pulse width PWmin. The minimum light intensity.

  Next, FIG. 6 is a flowchart showing a flow of light amount control in the light source device 40. The processing in FIG. 6 and FIGS. 7 and 8 described later is performed by the control unit 41 controlling each unit in the light source device 40.

  When this process is started, it is determined whether or not the light source control signal from the video processor 20 is to reduce the target light amount of the image (step S1).

  If it is determined that the light amount is to be decreased, a G light amount reduction process (step S2), an R light amount reduction process (step S3), and a B light amount reduction process (step S4) are performed. Note that the processes of steps S2 to S4 may be performed in an arbitrary order, or may be performed simultaneously.

  If it is determined in step S1 that the target light amount is not decreased, it is determined whether or not the target light amount of the image is increased (step S5).

  If it is determined that the target light amount is not to be increased, the target light amount is maintained as it is, so the process returns to step S1 to prepare for the processing of the next frame.

  On the other hand, if it is determined in step S5 that the target light amount is to be increased, G light amount increase processing (step S6), R light amount increase processing (step S7), and B light amount increase processing (step S8) are performed. . Note that the processes of steps S6 to S8 may be performed in an arbitrary order, or may be performed simultaneously.

  When the process of step S8 is thus performed, the process returns to step S1 to prepare for the processing of the next frame.

  Note that the R light quantity reduction process in step S3 is performed in substantially the same manner as the G light quantity reduction process in step S2 (see FIG. 7), and thus detailed description thereof is omitted. Further, since the G, R, B light quantity increasing process in steps S6 to S8 is performed as the reverse process of the G, R, B light quantity reducing process in steps S2 to S4, detailed description will be omitted in the same manner.

  FIG. 7 is a flowchart showing details of the G light amount reduction process in FIG.

  When this process is started, it is determined whether or not the current control of the G-LED 44 is a current control region in which current dimming is performed (step S11).

  Here, when it is determined that the current control region is set, the third current value Ig applied to the G-LED 44 is decreased (step S12).

  Then, it is determined whether or not the target amount of G light has been reached (step S13).

  If it is determined that the target light amount has not been reached, it is further determined whether or not the third current value Ig has reached the minimum rated current value Imin (step S14).

  If it is determined that the minimum rated current value Imin has not been reached, the process returns to step S12 to further decrease the third current value Ig.

  On the other hand, if it is determined in step S11 that the current control region is not reached, or if it is determined in step S14 that the minimum rated current value Imin has been reached, the control of the G-LED 44 is shifted to pulse width dimming, The pulse width PWg is decreased (step S15).

  Then, it is determined whether or not the target amount of G light has been reached (step S16).

  If it is determined that the target light amount has not been reached, it is further determined whether or not the pulse width PWg has reached the minimum pulse width PWmin (step S17).

  If it is determined that the minimum pulse width PWmin has not been reached, the process returns to step S15 to further decrease the pulse width PWg.

  Thus, if it is determined in step S17 that the minimum pulse width PWmin has been reached, or if it is determined in step S13 or step S16 that the target light amount of G light has been reached, the processing shown in FIG. Return.

  FIG. 8 is a flowchart showing details of the B light quantity reduction process in FIG.

  When this process is started, it is determined whether or not the current control of the first B-LD 45a and the second B-LD 45b is a current control region in which current dimming is performed (step S21).

  Here, when it is determined that the current control region is set, the first current value Ib1 applied to the first B-LD 45a and the second current value Ib2 applied to the second B-LD 45b are decreased (step S22). .

  Then, it is determined whether or not the target amount of B light has been reached (step S23).

  If it is determined that the target light amount has not been reached, it is further determined whether or not the first current value Ib1 and the second current value Ib2 have reached the speckle suppression current value Isp-th (step S24). ).

  If it is determined that the speckle suppression current value Isp-th has not been reached, the process returns to step S22 to further decrease the first current value Ib1 and the second current value Ib2.

  On the other hand, if it is determined in step S21 that the current control region is not reached, or if it is determined in step S24 that the speckle suppression current value Isp-th has been reached, first, the first pulse width of the first B-LD 45a is set. It is determined whether PWb1 is the minimum pulse width PWmin (step S25).

  If it is determined that the first pulse width PWb1 is not the minimum pulse width PWmin, the control of the first B-LD 45a is shifted to pulse width dimming to decrease the first pulse width PWb1 (step S26). ).

  Then, it is determined whether or not the target amount of B light has been reached (step S27).

  If it is determined that the target light amount has not been reached, it is further determined whether or not the first pulse width PWb1 has reached the minimum pulse width PWmin (step S28).

  If it is determined that the minimum pulse width PWmin has not been reached, the process returns to step S26 to further reduce the first pulse width PWb1.

  On the other hand, if it is determined in step S28 that the minimum pulse width PWmin has been reached, or if it is determined in step S25 that the first drive current is the minimum pulse width PWmin, the first current value Ib1 is waited for. The current value is set to Istby (step S29).

  Thereafter, the control of the second B-LD 45b is shifted to pulse width dimming, and the second pulse width PWb2 of the second drive current is decreased (step S30).

  Then, it is determined whether or not the target amount of B light has been reached (step S31).

  If it is determined that the target light amount has not been reached, it is further determined whether or not the second pulse width PWb2 has reached the minimum pulse width PWmin (step S32).

  If it is determined that the minimum pulse width PWmin has not been reached, the process returns to step S30 to further decrease the second pulse width PWb2.

  Thus, if it is determined in step S32 that the second pulse width PWb2 has reached the minimum pulse width PWmin, if it is determined in step S23, step S27, or step S31 that the target amount of B light has been reached, From this process, the process returns to the process shown in FIG.

  In the above description, the endoscope light source device 40 configured separately from the endoscope 10 has been described. However, the present invention is not limited to this. For example, the endoscope light source device 40 is provided in the endoscope 10. May be configured to be incorporated.

  In addition, in the above description, since two LDs that emit light of the same color are provided, the switching timing between current dimming and pulse width dimming is different for each LD. When a larger number of LDs are provided, two (or more) LDs may be grouped, and the switching timing of current dimming and pulse width dimming may be different for each group. Absent.

  According to the first embodiment, when the first current value Ib1 applied to the first B-LD 45a is larger than the speckle suppression current value Isp-th, current dimming is performed, and the speckle suppression current value Isp is performed. If the second current value Ib2 applied to the second B-LD 45b is greater than the speckle suppression current value Isp-th, the current dimming is performed. When the speckle suppression current value Isp-th is equal to the pulse width dimming control, the speckles of the first laser beam and the second laser beam can be satisfactorily suppressed.

  Since the first B-LD 45a and the second B-LD 45b are configured to generate laser beams of the same color, it is possible to realize good dimming characteristics by performing appropriate control.

  In addition, the first current value Ib1 and the second current value Ib2 are equal to the speckle suppression current value Isp-th, and the second pulse width PWb2 is maintained at the maximum pulse width of 100%, while maintaining the first pulse value Pbb2. Since the pulse width dimming with the pulse width PWb1 is performed, the gradation reproducibility can be improved while suppressing speckles.

  Further, while maintaining the state where the first pulse width PWb1 is the minimum pulse width PWmin, the second current value Ib2 is maintained equal to the speckle suppression current value Isp-th, and the second pulse width PWb2 Since pulse width dimming is performed, the dimming dynamic range can be widened with high gradation reproducibility.

  Then, since the first current value Ib1 is set to the standby current value Istby and then the pulse width dimming of the second pulse width PWb2 is performed, only one laser diode that emits B light is provided. Low light intensity that cannot be achieved in some cases can be achieved while suppressing speckle.

  In addition, a G-LED 44 that generates G light (or an R-LED 43 that generates R light) is provided, and the first intensity Sb of B light and the second intensity Sg of G light (or the first intensity of R light). Since the B light and G light (or R light) are maintained at a predetermined color balance based on the intensity Sr) of 2), the white balance of the illumination light is made constant even if light control is performed. Can do.

  In addition, since the first pulse width PWb1 in the current frame is set based on the intensity ratio {Sg / Sg (F3)}, color balance control is performed based on the second intensity Sg of G light. Can be controlled.

  In particular, the first pulse width of the current frame is set to PWb1 = [{Sg / Sg (F3)} × 200-100] while maintaining the second pulse width at PWb2 = 100%. The color balance can be appropriately maintained while individually controlling the LD 45a and the second B-LD 45b.

  Furthermore, since control was performed to set the first pulse width PWb1 in the current frame based on the pulse width ratio {PWg / PWg (F5)} and the first pulse width PWb1 (F5), Color balance control based on the third pulse width PWg can be performed, and control is simplified.

  In particular, the first pulse width of the current frame is maintained as PWb1 = ([{PWg / PWg (F5)} × {PWb1 (F5) +100}] − 100) while maintaining the second pulse width at PWb2 = 100%. By setting to, the color balance can be appropriately maintained while individually controlling the first B-LD 45a and the second B-LD 45b.

  When PWb1 = PWmin, Ib1 = Istby is set and pulse width dimming with the second pulse width PWb2 is performed, so that only one laser diode that emits B light is provided. The low light quantity that cannot be achieved can be achieved while suppressing speckles.

  In addition, by setting the second pulse width of the current frame to PWb2 = {100 × PWg / PWg (F8)}, the second pulse width PWb2 of the G light can be set with reference to the third pulse width PWg of G light. Color balance control by pulse width dimming can be easily performed.

  In addition, since the color balance is controlled based on the first intensity Sb detected by the B light sensor 45s and the second intensity Sg detected by the G light sensor 44s, the color balance is controlled based on the actual measurement value. It becomes possible to control the accuracy. Thereby, for example, even when the temperature changes and the light emission intensity of each light emitting element changes, an accurate white balance can be maintained.

  The first laser beam detector that detects the intensity of the first laser beam generated by the first B-LD 45a and the second laser beam that detects the intensity of the second laser beam generated by the second B-LD 45b. When the detector is provided separately, the intensity of the light generated by each detector can be accurately measured.

  On the other hand, when the intensity of the combined light obtained by adding the first laser light and the second laser light is detected by one laser light detector (B optical sensor 45s), the configuration can be simplified. it can.

[Embodiment 2]
FIGS. 9 and 10 show Embodiment 2 of the present invention. FIG. 9 is a timing chart showing how each light emitting element is driven according to B color light and G color light when dimming from the maximum light amount to the minimum light amount. It is a chart.

  In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted as appropriate, and only different points will be mainly described.

  In the first embodiment described above, the control unit 41 controls whether the current dimming or the pulse width dimming is set individually in the first application unit and the second application unit. . On the other hand, in the present embodiment, the control unit 41 sets whether the current dimming or the pulse width dimming is set to be the same for the first application unit and the second application unit. I have control.

  Control for dimming from the maximum light amount shown in FIG. 9 to the minimum light amount will be described in comparison with the control shown in FIG. 3 of the first embodiment. In addition, in order to demonstrate control of B light on the basis of G light, the description regarding R-LED43 is abbreviate | omitted in FIG.

  First, for the G-LED 44, current dimming is performed in the frames F1 to F5, and pulse width dimming is performed in the frames F6 to F10, which is substantially the same as in FIG.

  The control of the frames F1 to F3 is the same as that in FIG. 3, and the control unit 41 performs the first control that causes the light source driving unit 42 to perform current dimming of the first B-LD 45a and the second B-LD 45b.

  In the frame F3, the first current value Ib1 and the second current value Ib2 both reach the speckle suppression current value Isp-th.

  In subsequent frames F4 to F7, the control unit 41 causes the light source driving unit 42 to maintain the state where the first current value Ib1 and the second current value Ib2 are equal to the speckle suppression current value Isp-th. The first pulse width PWb1 and the second pulse width PWb2 are controlled so as to perform pulse width dimming.

  Specifically, in the frames F4 to F5, the control unit 41 multiplies the intensity ratio {Sg / Sg (F3)} by the maximum pulse width 100% of the first pulse width PWb1 {100Sg / Sg (F3)}. Are set to the first pulse width PWb1 and the second pulse width PWb2 in the current frame.

  Accordingly, in the frames F4 to F5, if the pulse width common to the first pulse width PWb1 and the second pulse width PWb2 is PWb, PWb = {100Sg / Sg (F3)}.

  In the frame F5, the third current value Ig reaches the minimum rated current value Imin of the G-LED 44.

  Therefore, in the frames F6 to F7, the control unit 41 multiplies the pulse width ratio {PWg / PWg (F5)} by the first pulse width {PWb (F5)} in the frame F5 {PWb (F5) · PWg / PWg (F5)} is controlled to be set to the first pulse width PWb1 and the second pulse width PWb2 in the current frame.

  Therefore, in frames F6 to F7, PWb = {PWb (F5) · PWg / PWg (F5)} is set.

  In the frame F7, the common pulse width PWb reaches the minimum pulse width PWmin.

  Here, in the present embodiment, processing for giving priority to the light control dynamic range over white balance is performed.

  That is, when control for further reducing the amount of light is required, the control unit 41 maintains the common pulse width PWb at the minimum pulse width PWmin and the first current value Ib1 and the first current value as shown in the frame F8. The second current value Ib2 is set to the standby current value Istby, and the first B-LD 45a and the second B-LD 45b are substantially non-light-emitting. Then, the control unit 41 performs pulse width dimming of the third pulse widths PWg and PWr while maintaining the third current values Ig and Ir of the G-LED 44 (and R-LED 43) at the minimum rated current value Imin. By doing so, the amount of illumination light is controlled.

  In this way, the third light pulse width PWg, PWr becomes the minimum light amount in the frame F10 in which both reach the minimum pulse width PWmin.

  Next, FIG. 10 is a flowchart showing processing for reducing the B light amount in the endoscope light source device 40.

  When this process is started in step S4 of FIG. 6, first, the processes of steps S21 to S24 as described with reference to FIG. 8 are performed.

  If it is determined in step S21 that the current control region is not reached, or if it is determined in step S24 that the speckle suppression current value Isp-th has been reached, first, the first pulse width PWb1 and the second pulse width PWb1 It is determined whether or not the pulse width PWb2 is the minimum pulse width PWmin (step S25A).

  When it is determined that the first pulse width PWb1 and the second pulse width PWb2 are not the minimum pulse width PWmin, the control of the first B-LD 45a and the second B-LD 45b is shifted to pulse width dimming, The first pulse width PWb1 and the second pulse width PWb2 are decreased (step S26A).

  Then, it is determined whether or not the target amount of B light has been reached (step S27A).

  If it is determined that the target light amount has not been reached, it is further determined whether or not the first pulse width PWb1 and the second pulse width PWb2 have reached the minimum pulse width PWmin (step S28A).

  If it is determined that the minimum pulse width PWmin has not been reached, the process returns to step S26A to further decrease the first pulse width PWb1 and the second pulse width PWb2.

  If it is determined in step S28A that the minimum pulse width PWmin has been reached, or if it is determined in step S25A that the first pulse width PWb1 and the second pulse width PWb2 are the minimum pulse width PWmin. The first current value Ib1 and the second current value Ib2 are set to the standby current value Istby (step S29A).

  Note that if the condition that it is larger than 0 and lower than the minimum rated current value Ith of the first B-LD 45a is satisfied, the standby current value Istby of the first current value Ib1 and the standby current value Istby of the second current value Ib2 May be different.

  When the process of step S29A is performed, when it is determined in step S23 or step S27A that the target amount of B light has been reached, the process returns to the process shown in FIG.

  According to the second embodiment, the same effects as those of the first embodiment described above are obtained, and the first pulse width PWb1 and the second pulse width PWb2 are both set to {100Sg / Sg (F3)}. By doing so, it is possible to appropriately maintain the color balance based on the second intensity Sg of the G light while performing the same control on the first B-LD 45a and the second B-LD 45b.

  Furthermore, by setting both the first pulse width PWb1 and the second pulse width PWb2 to {PWb (F5) · PWg / PWg (F5)}, the first B-LD 45a and the second B-LD 45b are the same. While performing the control, the color balance can be appropriately maintained based on the third pulse width PWg of the G light.

  Note that the processing of each unit described above may be performed by one or more processors configured as hardware. For example, each unit may be a processor configured as an electronic circuit, or may be each circuit unit in a processor configured by an integrated circuit such as an FPGA (Field Programmable Gate Array). Alternatively, a processor constituted by one or more CPUs may execute the functions of each unit by reading and executing a processing program recorded on a recording medium.

  In the above description, the endoscope light source device has been mainly described. However, an operation method for operating the endoscope light source device as described above may be used, or the computer may perform the same processing as the endoscope light source device. Or a non-temporary recording medium that can be read by a computer that records the processing program.

  Furthermore, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various aspects of the invention can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined. Thus, it goes without saying that various modifications and applications are possible without departing from the spirit of the invention.

  This application is filed on the basis of priority claim of Japanese Patent Application No. 2018-33060 filed in Japan on February 27, 2018, and the above-mentioned disclosure content includes the present specification, claims, It shall be cited in the drawing.

Claims (12)

A first drive current is applied, and a first laser beam having an intensity corresponding to the current value of the first drive current is generated as part of the illumination light from the endoscope inserted into the subject. 1 laser light source;
A first application unit configured to apply the first drive current having a first pulse current width equal to or less than a maximum rated current value of the first laser light source to the first laser light source;
The second drive current is applied, and the second laser beam having the intensity corresponding to the current value of the second drive current is the same as the color of the first laser beam. A second laser light source generated as part of the illumination light from
A second application unit that applies the second drive current having a second pulse width and a second current value equal to or less than a maximum rated current value of the second laser light source to the second laser light source;
A third driving current is applied, and light of a second color different from the first color having an intensity corresponding to the current value of the third driving current is used as one of the illumination lights from the endoscope. A light source generated as a part,
A third applying unit for applying the third drive current having a third pulse value with a third current value equal to or less than a maximum rated current value of the light source to the light source;
A first threshold value that is set to suppress speckle of the first laser light and that is a current value larger than a minimum rated current value of the first laser light source, and a spec of the second laser light. And the second threshold value, which is set to suppress the noise and is a current value larger than the minimum rated current value of the second laser light source, the first current value is When larger than the threshold value, the first application unit is controlled to perform current dimming with the first pulse width as the maximum pulse width, and the second current value is larger than the second threshold value. If larger, the second application unit is controlled to perform current dimming with the second pulse width as the maximum pulse width, and current dimming is performed on the first application unit and the second application unit. When performing the first control to be performed, the first current value is the first threshold value. And the second current value is equal to the second threshold value, and when the control for further reducing the amount of light is required, the second application unit is connected to the second application unit. Current value is equal to the second threshold value and the second pulse width is the maximum pulse width, while maintaining the state where the first current value is the first threshold value. A light source control unit that shifts to a second control that controls to perform pulse width dimming while maintaining a state equal to
I have a,
The light source control unit performs current dimming when the third current value is larger than the minimum rated current value of the light source, and performs pulse width dimming when equal to the minimum rated current value of the light source. And controlling the third application unit,
The light source control unit is configured to control the first color light and the second color based on a first intensity of the first color light and a second intensity of the second color light. The first application unit, the second application unit, and the third application unit are controlled so that light is maintained in a predetermined color balance, and light amount control is performed in units of frames. ,
When the light source controller performs control to reduce the light amount while maintaining the predetermined color balance, the light source is in a frame after the frame in which the first current value has reached the first threshold value. , The minimum rated current value is set so that the third current value reaches the minimum rated current value,
The light source controller controls the current frame based on the intensity ratio when the third application unit performs control for reducing the amount of light while maintaining the predetermined color balance. Controlling to set the first pulse width at
Here, the intensity ratio is determined in a frame in which the first pulse width reaches the first threshold value with the maximum pulse width and the second pulse width reaches the second threshold value with the maximum pulse width. An endoscopic light source device characterized by a ratio of the second intensity as a target in the current frame to the second intensity .   The light source control unit, when performing the second control, when the first pulse width becomes the minimum pulse width, and when the control to further reduce the light amount is necessary, A state in which the second current value is equal to the second threshold value in the second application unit while the first application unit maintains a state in which the first pulse width is the minimum pulse width. The endoscope light source device according to claim 1, wherein the process shifts to a third control for controlling the pulse width dimming while maintaining the same.   When the light source control unit shifts to the third control, first, the first application unit is caused to make the first current value larger than 0 than the minimum rated current value of the first laser light source. 3. The endoscope light source device according to claim 2, wherein the control is performed so that pulse width dimming is performed by the second application unit after that.   The light source control unit performs a control to reduce the light amount while maintaining the predetermined color balance when the third application unit performs a pulse width dimming on the frame, and the pulse width ratio and the first Control to set the first pulse width in the current frame based on the first pulse width in the frame in which the current value of 3 has reached the minimum rated current value of the light source,
  2. The endoscope according to claim 1, wherein the pulse width ratio is a ratio of the target third pulse width in the current frame to a maximum pulse width of the third pulse width. Mirror light source device.   The light source control unit controls whether to perform current dimming or pulse width dimming so as to be individually set in the first application unit and the second application unit,
  Further, the light source control unit is configured to multiply the intensity ratio by twice the maximum pulse width of the first pulse width while maintaining the second pulse width at the maximum pulse width. 2. The endoscope light source device according to claim 1, wherein a value obtained by subtracting a maximum pulse width of the first pulse width is controlled to be set to the first pulse width in a current frame.   The light source control unit controls whether to perform current dimming or pulse width dimming so as to be individually set in the first application unit and the second application unit,
  Further, the light source control unit maintains the second pulse width at the maximum pulse width, and the first pulse width in the frame in which the third current value has reached the minimum rated current value of the light source. The value obtained by subtracting the maximum pulse width of the first pulse width from the value obtained by multiplying the maximum pulse width of the first pulse width by the pulse width ratio is the value in the current frame. The endoscope light source device according to claim 4, wherein control is performed so as to set the first pulse width.   The light source control unit increases the first current value to be greater than 0 when the first pulse width becomes the minimum pulse width and control for further reducing the light amount is necessary. A standby current value lower than the minimum rated current value of the laser light source 1 is controlled to perform pulse width dimming of the second pulse width,
  Further, the light source control unit has a ratio of the target third pulse width in the current frame to the third pulse width in the frame in which the first current value is set to the standby current value. The endoscope light source device according to claim 6, wherein the second pulse width multiplied by the maximum pulse width is controlled to be set to the second pulse width in the current frame.   A first light detection unit that receives the first laser light and the second laser light and detects the first intensity of the incident light;
  A second light detection unit that receives light generated by the light source and detects the second intensity of the incident light;
  Further comprising
  The light source controller controls the first intensity detected by the first light detector to control the first color light and the second color light to maintain the predetermined color balance. The endoscope light source device according to claim 1, wherein the endoscope light source device is performed based on the second intensity detected by the second light detection unit.   The first light detection unit receives the first laser light, the first laser light detector that detects the intensity of the incident first laser light, and the second laser light is incident. The endoscope light source device according to claim 8, further comprising: a second laser beam detector configured to detect an intensity of the incident second laser beam.   The first light detection unit includes a laser light detector that receives a combined light obtained by adding the first laser light and the second laser light and detects the intensity of the incident combined light. The endoscope light source device according to claim 8.   A first drive current is applied, and a first laser beam having an intensity corresponding to the current value of the first drive current is generated as part of the illumination light from the endoscope inserted into the subject. 1 laser light source;
  A first application unit configured to apply the first drive current having a first pulse current width equal to or less than a maximum rated current value of the first laser light source to the first laser light source;
  The second drive current is applied, and the second laser beam having the intensity corresponding to the current value of the second drive current is the same as the color of the first laser beam. A second laser light source generated as part of the illumination light from
  A second application unit that applies the second drive current having a second pulse width and a second current value equal to or less than a maximum rated current value of the second laser light source to the second laser light source;
  A third driving current is applied, and light of a second color different from the first color having an intensity corresponding to the current value of the third driving current is used as one of the illumination lights from the endoscope. A light source generated as a part,
  A third applying unit for applying the third drive current having a third pulse value with a third current value equal to or less than a maximum rated current value of the light source to the light source;
  A first threshold value that is set to suppress speckle of the first laser light and that is a current value larger than a minimum rated current value of the first laser light source, and a spec of the second laser light. And the second threshold value, which is set to suppress the noise and is a current value larger than the minimum rated current value of the second laser light source, the first current value is When it is larger than the threshold value, the first pulse width is set to the maximum pulse width to perform current dimming, and when equal to the first threshold value, the first application unit is controlled to perform pulse width dimming. When the second current value is larger than the second threshold value, current dimming is performed with the second pulse width set to the maximum pulse width, and when the second current value is equal to the second threshold value, pulse width dimming is performed. The second application unit is controlled so that the third current value is If greater than the minimum rated current value of the light source performs current dimming, equal to the minimum rated current value of the light source and the light source control section for controlling the third application unit to perform pulse width dimming,
  Have
  The light source control unit is configured to control the first color light and the second color based on a first intensity of the first color light and a second intensity of the second color light. The first application unit, the second application unit, and the third application unit are controlled so that light is maintained at a predetermined color balance, and light amount control is performed in units of frames. The current dimming or the pulse width dimming is controlled so as to be set to be the same for the first application unit and the second application unit,
  When the light source controller performs control to reduce the light amount while maintaining the predetermined color balance, the light source is in a frame after the frame in which the first current value has reached the first threshold value. , The minimum rated current value is set so that the third current value reaches the minimum rated current value,
  Further, the light source control unit performs the control to reduce the light amount while maintaining the predetermined color balance, when the third application unit performs the current dimming on the frame that performs the current dimming, the intensity ratio includes the first light intensity control unit. A value obtained by multiplying the maximum pulse width by the pulse width of the first frame is controlled to be set to the first pulse width and the second pulse width in the current frame.
  Here, the intensity ratio is determined in a frame in which the first pulse width reaches the first threshold value with the maximum pulse width and the second pulse width reaches the second threshold value with the maximum pulse width. An endoscopic light source device characterized by a ratio of the second intensity as a target in the current frame to the second intensity.   The light source control unit performs the control to reduce the amount of light while maintaining the predetermined color balance when the third application unit performs a pulse width dimming on the frame having the pulse width ratio. A value obtained by multiplying the first pulse width in the frame in which the current value of 3 reaches the minimum rated current value of the light source is set to the first pulse width and the second pulse width in the current frame. To control,
  12. The endoscope according to claim 11, wherein the pulse width ratio is a ratio of the target third pulse width in the current frame to a maximum pulse width of the third pulse width. Mirror light source device.

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